BAEL-3688: Add examples of a constructor and a setter injection types (#8452)

spring-core-2/src/main/java/com/baeldung/autowire/sample/FooService.java

@@ -3,6 +3,10 @@ package com.baeldung.autowire.sample;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Component;
 
+/**
+ * This class presents a field, a constructor, and a setter injection type.
+ * Usually, we'd stick with a single approach for a given property. This is just an educational code.
+ */
 @Component
 public class FooService {
 
@@ -10,6 +14,16 @@ public class FooService {
     @FormatterType("Foo")
     private Formatter formatter;
 
+    @Autowired
+    public FooService(@FormatterType("Foo") Formatter formatter) {
+        this.formatter = formatter;
+    }
+
+    @Autowired
+    public void setFormatter(@FormatterType("Foo") Formatter formatter) {
+        this.formatter = formatter;
+    }
+
     public String doStuff() {
         return formatter.format();
     }